The complexity of the contamination at the Terry Creek Superfund site adds to the challenge of educating the public about what’s at stake for them and the health of their families and environment.
There are 34 sites at Pinova’s plant in Brunswick where work is being done to remediate contaminated soil.
Among these, the toxaphene tank farm is a priority, Geosyntec Environmental Engineer Ali Ciblak said in one of two virtual public meetings this spring.
The draft cleanup plan for that area involves a process called “in-situ solidification,” which means mixing binding agents like cement with the contaminated soil to keep it in place and prevent it from spreading or spilling.
Unlike excavating and removing contaminated soil, in-situ solidification would not threaten the structural integrity of nearby buildings, he said. It also would be less disruptive to Pinova’s business operations, according to the company.
Another environmental hazard to be addressed at the site is vapor intrusion, which occurs when contamination in shallow groundwater volatizes – turns into vapors – and migrates up toward the foundation of a building. Such transference could expose occupants to pollution.
Todd Creamer, a vapor intrusion specialist for Geosyntec, said the threat is only a problem at Pinova and not off-site. For now, the threat is handled by industrial fans pulling air from a pipe that leads to the foundation, Creamer said. A carbon drum filter on the pipe catches air contamination.
The Upper Surficial aquifer, the water table that spans from two feet beneath the surface of the plant to 100 feet, also is a focus of remediation efforts on site. Drinking water comes from wells 700 – 1,000 feet deep in the Floridan aquifer system.
Geosyntec discovered groundwater close to the surface shifts along a slight slope that causes it to flow from west to east at a rate of about 50 feet per year. A chemical compound called Benzene lingers in the water there.
The colorless chemical dissolves only slightly in water. It is both naturally occurring and man-made. In vapor form, Benzene is heavier than air, but as a liquid it floats on top of water. The chemical can cause cancer, low animal birth weight and affects red blood cell production in humans, according to the CDC.
One way to reduce the amount of Benzene in the water table is through a process called chemical oxidation. The method involves mixing an oxidant, activated sulfate, and injecting it into water wells. The oxidant is “capable of breaking chemical bonds … and destroying chemicals,” said Geosyntec Environmental Engineer Shanna Thompson, unrelated to Rachael Thompson.
“We’ll start in the inside of our treatment area here and then work out to the edges,” Shana Thompson said. “We’ll install monitoring wells around and within this injection area and we’ll look at changes.”
On deeper into the ground, at the Lower Surficial aquifer 100-200 feet below, a process called natural attenuation will be used to reduce contaminants.
“We’re actually stimulating the activity of degradative organisms that already exist, that will use our contaminations as a food substrate,” Geosyntec Microbiologist Duane Graves said.
Oxygen and other amendments will be injected into the groundwater to promote growth of a kind of bacteria that eats target chemicals like benzene and chlorobenzene in a process called bioremediation. Anaerobic bacteria, which thrive in the absence of oxygen, also will be injected to destroy contaminants like chloroform and help degrade lingering toxaphene.
“The interesting thing about chloroform degradation is the bacteria that degrade chloroform actually use it very similar to the way we use oxygen: They breathe the chloroform in essence, but in that process, they also degrade it,” Graves said.
In the end, a road of wells will create a permeable treatment wall, a filter called a bio reactive barrier, so that groundwater is treated as it flows east.
Additional details about the site and cleanup efforts are located at www.herculesbrunswick.com.
The period for public comment ends May 10, 2021. The draft plan will be revised based on comments received. Comments may be emailed to Jim.Sliwinski@dnr.ga.gov.